Remote control system



Oct. 2, 1934. DIXON I 1,975,653

REMOTE CONTROL SYSTEM Filed March 5, 1951 big- Z INVENTOR. H, /\f. D 1 X o n,

1 Qa-W Patented Get. 2, 1934 REMOTE CONTROL SYSTEM Howell N. Dixon, Swissvale, Pa, assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporationot Pennsylvania Application March 3,

18 Claims.

My invention relates to remote control systems of the type involving a control station and a plurality of remote or field stations connected by one or more line circuits. One object of my invention is the provision, in a system of this character, of a repeating o-r relaying station located at a point between the control station and the more remote stations, for the purpose of repeating each code that is sent out from the control station, and also each code that is generated at a field station more remote than the repeating station.

A repeating or relaying station is desirable when a remote control system involves line circuits of such length as to introduce a handicap due to line resistance and leakage. In such cases the repeating station or stations may be located at any point or points where it is convenient to house the relays and batteries associated therewith.

I will describe one form of repeating station embodying my invention, and will then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic View showing one form of repeating station embodying my invention.

In the present instance the repeating station is illustrated as applied to a centralized trafiic control system of the type involving three line Wires X, Y and Z. On the primary side of the repeating station these Wires are designated 1X, lY and 1Z; on the secondary side of the station they are designated 2X, 21 and 22. In systems of the character contemplated by the present invention, the wire 1X is connected to a battery at the control station, and it then passes through a line relay at the control station and a line relay at each intermediate field station, until it reaches the repeating station, at which point it is connected to the wire 12 which has a common return to the other terminal of the battery at the control station. Similarly, wire lY is connected with a battery at the control station, with a relay at such station, and a relay at each field station, until it reaches the repeating station at which point it is connected to the common return wire 12. One system arranged as specified I above is disclosed and claimed in an application for Letters Patent of the United States Serial No. 538,380, filed May 18, 1931, by C. S. Snavely, A. B. Miller and R. H. Tunell, for Remote control systems. This system is described in a book entitled Centralized Trafiic Control System- Circuit Code Scheme dated April, 1931, and published by The Union Switch & Signal Company, Swissvale, Pennsylvania.

The repeating station involves three line re- 7 lays lRX, lRYand 1R2 on the primaryside, and three other line relays ZRX, ZRY and 2RZ on the 1931, Serial No. 519,709

secondary side. These relays are all alike except that relays lRZ and 232 are preferably designed to release in a slightly shorter time than the other R relays. The station also involves three primary directional repeating relays lXP, IYP and lZP; and three secondary directional repeating relays ZXP, 2YP and 2ZP. On the primary side are three bridging relays lXB, lYB and 12B; and on the secondary side are three bridging relays ZXB, ZYB and 22.13. A slow-releasing relay lR-ZP is provided to bridge the time interval between each two "impulses, and to restore the repeating station to its normal condition after a field station beyond the repeating station has transmitted an indication code.

The functions that are required of the repeating station are First, to repeat the control codes that are generated at the central station and transmit them to the field stations beyond the repeating station. Second, to cause the normal operation of all field stations beyond the repeating station when the control station is transmitting a control code to a less remote field station. Third, to repeat the indication codes that are generated at all more remote field stations. Fourth, to cause the deenergization of allmore remote line relays from a less remote field station when the latter station is transmitting an indication code.

In the circuit code system to which I have referred, codes generated at the control station and at each field station consist of X, Y andZ impulses arranged in diiIerent orders, and so it will only be necessary to explain the action of these three impulses. I will assume (1) that Z, X and Y are the first three impulses of a given control code, (2) that X, Y and Z are the first three impulses of a given indication code, and (3) that a more remote field station transmits an indication code through the repeating station.

The circuit code system furthermore, operates in such a manner that each time one of the lines X, Y or Z is opened at a transmitting station, the resulting release of the line relays causes the corresponding line to be opened at each receiving station also, and the line is held open at the receiving stations until the impulse has been registered by the operation of the proper relays at such stations. Thus the transmitting and receiving stations are held in synchronism by the action of the receiving stations.

The repeater of my invention includes a novel arrangement of circuits whereby if a secondary circuit is opened, as the result of the opening of a primary circuit, the primary circuit can not be closed again unless the secondary circuit is closed first. By virtue of this arrangement, my repeater when used with a remote control system of the type referred to not only provides the advantages of the usual one-way telegraph repeater in that it increases the available transmission distance, but it functions in such manner that receiving stations on one side of the repeater are able to govern the transmitting speed of a station on the other side of the repeater so that the two stations will be held in synchronism through the repeater.

As illustrated in the drawing, all parts of the apparatus are in their normal conditions, that is, the conditions which they assume when no code is being transmitted in either direction. Current coming in through line wire 1X passes through relay lRX, front contact 5 of relay ZRX, wire 25, front contact 3 of relay ZRZ, and relay lRZ to wire lZ. Similarly, current coming in on wire 11 passes through relay lRY, front contact 7 of relay 2RY, wire 25, front contact 3 of relay 2R2, and relay lRZ to wire lZ. Relays 2R2, ZRX and ZRY are so designed that when they become deenergized, contact 3, 5 or '7 will not open until back contact 40, 26 or 30 has closed.

On the secondary side, current from the secondary line battery 13 passes through line wire 22 and the remote field stations to the ultimate field station, from which it returns through wire 2Y and then passes through relay ZRY, front contact 8 of relaylRY, front contact 4 of relay lRZ, and relay ZRZ to battery 13. Similarly, current from battery 13 passes through the more remote field stations and returns through wire 2X, and it then passes through relay 2RX, front contact 6 of relay lRX, front contact 4 of relay lRZ, and relay 2R2 to battery 13. Relays lRZ, lRX and IRS? are so designed that when they become deenergized, contact 4, 6 or 8 will remain closed until after contact 39, 15 or 20 has closed.

7 The slow-releasing relay lRZP is provided with a circuit which passes from terminal B of a local source of current, through front contact 14 of relay lRZ, and the winding of relay lRZP to terminal 0 of the same source of current. It follows that relay lRZP is normally energized.

All of the directional repeating relays and the bridging relays are deenergized.

In order to initiate a Z impulse at the control station, the battery at that station is simultaneously disconnected for a brief interval of time from wires 1X and lY, thereby deenergizing relays lRX, lRY and lRZ. Inasmuch as relay lRZ will release before relays lRX and lRY, the relay lRZ will open at contact 4 the circuits for relays 2RZ, ZRX and ZRY. When relay lRZ releases, relay 12? will become energized, the circuit being from terminal B, through back contact 39 of relay lRZ, back contact 9 of relay 22F, and the winding of relay 12F to terminal 0. Relay 22B will then become energized, the circuit being from terminal B'through front point of contact 10 of relay lZP,

back contact 11 of relay 2RZ, front contact 12 of relay lRZP, and the winding of relay 2213 to ter- 'minal 0. 'It will be noted that relay 22GB cannot become energized unless relay 2RZ has released, and this insures that when a Z impulse is received at the repeater station, both primary line circuits are opened at the repeater station and held open until the secondary line circuits have been opened and the Z impulse has been transmitted to the remote stations on the secondary side. When relay 2ZB closes, its front contact 45 completes a branch path around contact 4 of relay lRZ. The opening of relay lRX closes a circuit for directional'selecting relay lXP, which circuit is from terminal B, through back contact 15, back contact 16, and the winding of relay-lzQto terminalO.

When relay lXP closes, it will complete a circuit to energize bridging relay 2XB, which circuit in cludes front contact 17 of relay lXP and back contact 18 of relay ZRX. Similarly, when relay lRY releases, it will cause relay lYP to become energized through contacts 20 and 21. When relay lYP becomes energized, it will cause relay 2YB to become energized through front contact 22 and back contact 23.

Relay lRZP is sufiiciently slow-acting to bridge the Z impulse, and so this relay does not release. 7 Since both secondary line circuits are now closed, current will now flow from the secondary line battery 13, through relay ZRZ, front contact 45 of relay 22B, wire 24, front contact 19 of relay 2X3, and winding of relay 2RX to the line wire 2X. Relays 2R2 and ZRX will, therefore, become energized. At the same time current will flow from battery 13 through relay ZRZ, contact 45 of relay ZZB, wire 24, contact 4-1 of relay ZYB, and the winding of relay ZRY, to line wire 2Y. Relay 2RY will, therefore also become energized. When relay 2RZ becomes energized, it will close at contact ,3 the normal circuit for relay lRZ, and the normal circuits for relays lRX and lRY will similarly be closed at front contacts 5 and 7, respectively, of relays 2RX and 2RY when the latter relays become energized. As already pointed out, battery is disconnected from the primary line cireuits only for a brief interval. This interval is preferably only long enough to reliably insure the release of each of the line relays. Since the repeater operation so far described includes the operation of several relays in sequence, it will consume a slightly greater time interval. It follows that battery will usually be connected to the primary circuits before these circuits are closed at the repeater station, so that when the repeater completes the primary circuits, relays lRZ, lRX and lRY will immediately become energized. Furthermore, when relay ZRZ closes, it will open at contact 11 the circuit for relay ZZB, so that this relay will again become deenergized. For similar reasons, relays 2XB and 2YB will also become deenergized. When relay lRZ becomes energized, it will deenergize relay IZP, andfor similar reasons, relays lXP and lYP will also become deenergized. The parts of the apparatus will then be restored to their normal conditions.

An X impulse is initiated at the control station by opening the wire 1X for a brief interval of time. This will .deenergize relay lRX, thereby opening the circuit for relay 2RX at contact 6 and so initiating an X impulse in the secondary line circuit. The opening of relay lRX will also energize relay lXP, and this will in turn energize relay 2X13. Contact 19 of relay 2X3 will then bridge the open front contact 6 in the circuit for relay ZRX, so that the latter relay will again become energized. The circuit for relay lRX will'then again be completed at contact 5 of relay ZRX, so

the foregoing explanation of an X impulse. That is to say, relay lRY will open, relay 2RY will open, relays lYP and ZYB will close, whereupon relayZRY will close, and finallyrelay lRY will close.

It is to be noted that since line Z provides a common return for the two lines X and Y, the simultaneous operation of the X and Y repeaters has the same effect as the operation of the Z repeater; and it might at first appear that the latter is superfluous. However, when working under unfavorable conditions, as for example, in the presence of line leakage, it has been found that the characteristics of the two lines may differ so that the two line relays in lines X and Y will not release at the same time when the primary circuits are opened simultaneously. By providing a separate repeater for line Z, I am enabled to open both secondary lines by the same contact, and hence simultaneously. The Z repeater therefore corrects any distortion present in the Z impulses in the primary circuit.

I will now assume that a field station on the secondary side of the repeating station transmits an indication code. When an X impulse of this code is received, it will deenergize relay ZRX, and the opening of this relay will open the circuit for relay lRX at contact 5. The opening of relay 2RX will energize relay ZXP, the circuit including back contact 26 of relay 23X and back contact 27 of relay lXP. When relay ZXP closes, it will energize relay lXB, the circuit including front contact 28 of relay ZXP and back contact 29 of relay lRX. Contact 42 of relay 1X5 will then bridge contact 5 of relay ZRX, so that relay lRX will again become energized. This will close the circuit for relay 2RX at contact 6, so that the latter relay will also become energized. Re-

' lays lXB and ZXP will then release, and the parts of the apparatus will be restored to their normal conditions. Relay lRZP does not function during this operation.

When a Y impulse of an indication code is received, relays ZBY and lRY will become deenergized, whereupon the relays associated therewith will function in a manner which will be obvious from the foregoing without detailed explanation.

When a Z impulse of an indication code is received, due to battery having been simultaneously disconnected for a brief interval of time from both wires 2X and 2Y at the remote transmitting station, all three line relays 2RX, 2RY and 2RZ will be simultaneously deenergized. This will open the circuits for primary relays lRX, lRY and lRZ at contacts 5, '7 and 3, respectively. Relay 2RZ will release slightly before relays 2RX and 2RY. The secondary directional relay 2ZP will become energized through back contact 40 of relay 2RZ and back contact 41 of relay 12?. This will cause relay lZB to become energized. The opening of relay ZRX will cause relay ZXP to become energized, and this will in turn energize relay lXB. The opening of relay 2RY will cause relay 2YP to become energized, and this will in turn energize relay lYB. With relays 1ZB, 12GB and lYB all energized, relays IRZ, lRX and lRY will again become energized, because their circuits will be completed through contacts 46, 42 and 43. The secondary line relays will then become energized, whereupon the B relays and the P relays will be deenergized, andthe apparatus will be restored to its normal condition.

It is clear from the foregoing that my repeater functions in such a manner that the opening of a primary line causes the corresponding secondary line to open and to then close, and that the closing of the secondary line permits the primary line to be closed, and that it functions in this manner for transmission in either direction.

When a field station on the primary side of the repeating station transmits an indication code to the control station, the primary circuits leading into the repeating station will be opened and will remain open during the transmission of such code. This will result in opening relays lRZ, lRX and lRY, thereby transmitting a Z impulse to all of the stations on the secondary side of the repeating station. After relay lRZ has been open for a given length of time, the slow-releasing relay lRZP will release. Immediately upon the release of the primary R relays, the primary directional P relays will become energized, thereby energizing the secondary bridging relays B. This will again close the secondary lines to permit the secondary line relays to pick up, and when these relays become energized the circuits for the secondary bridging relays will be again opened, so that Z impulses will be transmitted to the secondary lines repeatedly. This however is of no consequence, and the transmission of Z impulses will soon stop, because when relay lRZP releases, the circuit for relay 2Z3 will be opened at contact 12, thereby holding that relay deenergized. This will open the circuit for relay 2RZ at contact 45, and this will open the circuits for relays ZRX and ZRY, thereby deenergizing all relays in the secondary circuit. The opening of relay lRZP will close at back contacts 36, 37 and 38 auxiliary shunt paths around contacts 3, 5 and '7 of the secondary line relays, thereby allowing the primary line relays to become energized as soon as the indication code has been completed. When this occurs, the primary line relays will become energized, thereby energizing the secondary line relays, with the result that the directional relays and the bridging relays will become deenergized. Relay lRZP will again become energized, and all parts of the apparatus will be restored to their normal condi-- tions.

In remote control systems it may happen that any two stations will start to transmit a code at exactly the same time. In the circuit code system, to which reference has been made, proper operation under this condition is insured by beginning each control code with a Z impulse and each indication code with an X or a Y impulse, in arranging the apparatus at each field station so that if both lines extending from such station toward the control station open prior to or during the first impulse of a code the transmission of code from such station is withheld until both lines again become steadily closed, and by opening both lines extending in the opposite direction from such station for the duration of an indication code only. The arrangement described in the preceding paragraph relating to relay lRZP provides for transmitting a prolonged Z impulse through the repeater and thus prevents interference in the transmission from any 135 two field stations situated on opposite sides of the repeater. It is thus evident that when a repeater is used, it is quite possible that a primary circuit and a corresponding secondary circuit may become opened at exactly the same time. 140 This may occur, for example, it the control station starts to transmit a control code at the same instant that a remote station on the secondary side of the repeating station starts to transmit an indication code. Assuming, for example, that wires 1X and 2X are opened at the same instant, it is obvious that relays lRX and 23X will, likewise, release at the same instant and that, with the apparatus thus far described, neither one of the directional selecting relays lXP nor 2XP will .150

become fully energized. In the event that this condition should arise, it is desirable to energize relay IX? and keep relay ZXP deenergized, thereby allowing the control code to be transmitted by the control station and preventing the indication code from being transmitted by the remote station. For this reason, relay 1X9 is provided with an auxiliary circuit which passes from terminal "5, through front contact 47 of relay ZXP, front contact 48 of relay lXP, and the winding of the latter relay to terminal 0. Contact 47 of relay 2X? will close before contact 16 will open, and, similarly, contact 48 of relay 1X1 will close before contact 27 will open. It follows that if relays 13K and ZRX are simultaneously deenergized, relay lXP will become fully energized and will remain energized until relay IRX again becomes energized.

For a similar reason, relay lYP is provided with an auxiliary circuit which includes a front contact 49 of relay 2Y1 and a front contact 50 of relay lYP, these relays being so designed that contact l9 will close before contact 21 will open, and that contact 50 will close before contact 31 will open.

Although I have herein shown and described only one form of apparatus embodying my invention, it understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a remote control system of the type involving three line Wires X, Y and Z, a repeating station comprising three primary line relays included in the three line wires respectively on the primary side of the station, three secondary line relays included in the three line wires respectively on the secondary side of the station, means for normally connecting each primary line wire with each of the other primary line wires through front contacts of the corresponding secondary line relays, means for normally connecting each secondary line wire with each of the other secondary line wires through front con tacts of the corresponding primary line relays, a directional relay and a bridging relay for each line relay, a slow releasing relay, a circuit for each directional relay including a back contact of the associated line relay and a back contact of the corresponding directional relay on the other side of the station, a circuit for each bridging relay including a back contact of the associated line relay and a front contact of the corresponding directional relay on the other side of the station, the circuit for the secondary bridging relay for the Z wire also including a front contact of said slow releasing relay, a circuit for said slow releasing relay including a front contact of the primary line relay in the Z wire, a shunt around the first mentioned contact of each line relay including a front contact of the associated bridging relay on the other side of the station, and a second shunt around the first mentioned contact of each secondary line relay including said primary line relay and a front contact of the secondary line relay, a secondary line circuit including said secondary line relay and a front contact of said primary line relay, 2. directional relay and a bridging relay for each line relay, a circuit for each directional relay including a back contact of the associated line relay and a back contact of the other directional relay, a circuit for each bridging relay including a back contact of the associated line relay and a front contact of the directional relay associated with the other line relay, and a shunt around said front contact of each line relay including a front contact of the bridging relay associated with the other line relay.

3. A repeating station for a remote control system, comprising a primary line relay included in a primary circuit, a secondary line relay included in a secondary circuit, each circuit including a front contact of the relay for the other circuit whereby the opening of the primary circuit opens the secondary circuit and this in turn keeps the primary circuit open, auxiliary means responding tothe open condition of both of said relays to again close said secondary circuit, and means comprising a back contact of said secondary line relay for releasing said auxiliary means.

4. A repeating station for a remote control system, comprising, in combination with a primary circuit and a secondary circuit, means-responsive to the opening of either circuit for opening the other circuit, and auxiliary means responsive to the sequential opening of the primary and secondary circuits and effective only when both circuits are open for closing the secondary circuit independently of the first mentioned means.

5. A repeating station for a remote control system, comprising, in combination with a primary circuit and a secondary circuit, means responsive to the opening of either circuit for opening the other circuit, auxiliary means responsive to the sequential opening of the primary and secondary circuits and eifective only when both circuits are open for closing the secondary circuit independently of the first mentioned means, and other auxiliary means, responsive to the sequential opening of said secondary and primary circuits and effective only when both circuits are open for closing the pri'- mary circuit independently of said first mentioned means.

6. A repeating station for a remote control system comprising a primary line relay included in a primary circuit, a secondary line relay included in a secondary circuit, each circuit including a front contact of the relay for the other circuit, a normally open bridging relay, means ondary circuit around the primary line relay front contact including a front contact of said bridging relay.

'7. A repeating station for a remote control system comprising a primary line relay included in a primary circuit, a secondary line relay included in a secondary circuit, each circuit including a front contact of the relay for the other circuit, a normally open bridging relay, 'means for closing said bridging relay in response to the sequential opening of said primary and secondary line relays, a branch for the secondary circuit around the primary line relay front contact including a front contact of said bridging relay, and means including a slow releasing relay controlled by the primary line relay for opening said bridging relay when the primary circuit is open for a period longer than that required for the transmission of a control impulse.

8. A repeating station for a remote control system, comprising, in combination with a primary circuit and a secondary circuit, means responsive to the opening of either circuit for opening the other circuit, auxiliary means responsive to the sequential opening of the primary and secondary circuits and effective only when both circuits are open for closing the secondary circuit independently of the first mentioned means, other auxiliary means responsive to the sequential opening of said secondary and primary circuits and effective only when both circuits are open for closing the primary circuit independently of said first mentioned means, and means responsive to simultaneous opening of said primary and secondary circuits for permitting said first auxiliary means to function and preventing said second auxiliary means from functioning.

9. A repeating station for a remote control system comprising a primary line relay and a secondary line relay, a primary line circuit including said primary line relay and a front contact of the secondary line relay, a secondary line circuit including said secondary line relay and a front contact of said primary line relay, a directional relay and a bridging relay for each line relay, a circuit for each directional relay including a back contact of the associated line relay and a back contact of the other directional relay, an auxiliary circuit for the primary directional relay including its own front contact and a front contact of the other directional relay, a circuit for each bridging relay including a back contact of the associated line relay and a front contact of the associated directional relay, and a shunt around said front contact of each line relay including a front contact of the bridging relay associated with the other line relay.

10. A repeater for a remote control system having two line circuits, comprising a line relay in each line circuit having a front contact in the other line circuit, whereby the momentary opening of either line circuit at a remote point will cause the other line circuit to open and thereby hold both circuits open; line restoring means comprising a bridging relay for each line relay, means operable when one of the line relays releases to selectively energize the corresponding bridging relay as soon as the other line relay is released, and means including a front contact of said bridging relay for bridging the front contact of said one line relay to permit the other line relay to become energized.

11. A repeater for repeating impulses in either direction from one line circuit to another line circuit, comprising means responsive to the momentary opening of either one of said line circuits to momentarily open the other line circuit, and to hold said one line circuit open until the other line circuit becomes closed, and means re sponsive to the successive opening of said line circuits to again close said other line circuit.

12. A repeater for two line circuits each including a line relay, comprising a normally closed contact included in each line circuit and coni trolled by the line relay for the other line cir- 13. A repeater for two line circuits each including a line relay, comprising a normally closed contact included in each line circuit and controlled by the line relay for the other line circuit, a shunt for each contact, means operating when both line relays are deenergized to close the shunt for the contact of the second line relay to become deenergized, and other means for shunting a particular one of said contacts and for preventing the shunting of the other, effective when one line or the other is opened for a prolonged time .interval.

14. In combination with two line circuits each including a normally energized line relay and a normally closed contact controlled by the line relay of the other line circuit; means resposive to the momentary opening of either circuit and the consequent release of the line relays of both circuits for effecting the closing of said circuits in an order the reverse of that in which they were opened.

15. In combination with two line circuits each including a normally energized line relay and a normally closed contact controlled by the line relay of the other line circuit; means responsive to the momentary opening of either circuit and the consequent opening of the other line circuit for preventing the line circuit which was first opened from becoming closed until said other line circuit is closed, whereby the reenergization of the line relay in each line circuit is made dependent upon the continuity of the other line circuit.

16. In combination with two line circuits each including a normally energized line relay and a normally closed contact controlled by the line relay of the other line circuit; means responsive to the momentary opening of either circuit and the consequent release of the line relays of both circuits for effecting the closing of said circuits in an order the reverse of that in which they were opened, and means responsive to the prolonged opening of one of said control contacts for maintaining the other line circuit open until said control contact is closed.

17. A repeater for two line circuits each including a normally energized line relay, comprising a normally closed contact in each line circuit controlled by the line relay of the other line circuit, and restoring means effective when both line circuits have been opened for closing said normally closed contacts, said restoring means including means for bridging the normally closed contact in one line circuit only to permit the energization of the lin relay in such line circuit when such line circuit is closed at all other points.

18. In combination with a pair of independently operable normally open contacts, a pair of interconnected relays, a pickup circuit for each relay including one of said normally open contacts and also a back contact of the other relay, whereby the energization of either relay opens the pickup circuit of the other relay; and a holding circuit for one of said relays only, closed only when both relays are picked up, whereby said one relay will be held energized until the other relay is released to again close the pickup circuit of said one relay, in the event of the closing of both of said normally open contacts at substantially the same time.

HOWELL N. DIXON. 

